www.networkforgood.org (Network for Good) is a portal that allows you to use a credit card to make a donation without the charity being dinged for any credit card fees (100% of the donation goes to the charity). I just made my 2002 church pledge and got a mess of miles in addition to the normal warm and fuzzies associated with a donation.

I suspect that it is easy to get your favorite non-credit-card-accepting charity added to this site.